Compact heat pump using water as refrigerant

ABSTRACT

According to the present invention there is provided a compact heat pump using water as refrigerant, comprising an evaporator located at a first end section of the heat pump casing, adapted to allow evaporation of water therefrom, One or more compressors located at a second end section of the heat pump casing adapted to induce said evaporation by maintaining vacuum, provided with an intake conduit extending from the evaporator to the compressor leading vapor thereto. A condenser is located in the intermediate section of the casing wherein the intake conduit passes therethrough, adapted for condensing the vapor. The heat pump also comprises vacuum means allowing creating and maintaining vacuum in the casing. There is also provided a snow dome allowing skiing and snow related activities in above zero conditions using the heat pump for creation of snow or ice slurry.

FIELD OF THE INVENTION

This invention relates to vacuum heat pumps, in particular those thatuse water as refrigerant.

BACKGROUND OF THE INVENTION

A heat pump is a mechanism designed to displace a certain amount of heatenergy from a low temperature environment to a high temperatureenvironment by applying work to the refrigerant.

A heat pump may work in an open or closed cycle. In a closed cycle, thepump's functional components form a closed loop through which therefrigerant is cycled over and over again, and in the course of whichheat is taken away or given to the refrigerant, respectively heating orcooling the environment outside the heat pump. In open cycle heat pumps,the components are normally arranged along a line for the refrigerant tobe driven through the components until it exits the system all together,thereby removing heat from the refrigerant at one end of the line andreleasing it at the other end. This kind of cycle requires a constantfeed of new refrigerant on one end, and extraction of transformedrefrigerant on the other end.

A vacuum heat pump usually comprises an evaporator adapted toaccommodate a liquid refrigerant to be evaporated therefrom, acompressor adapted to induce the evaporation and compress the vapor, anda condenser adapted to transform the vapor coming from the compressorback into a liquid state. In such a heat pump, a compressor or anejector is responsible for maintaining the vacuum needed to induceevaporation. As a result, a part of the refrigerant in the evaporatorevaporates, much like sweat from our body, removing heat from theremainder of the refrigerant, and the evaporated refrigerant is normallycondensed in the condenser so that both the cooled refrigerant thatremains in the evaporator, and the condensate, may be used for a varietyof implementations.

One vacuum heat pump of this kind is disclosed in the Applicant's U.S.Pat. No. 6,688,117.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided acompact heat pump using water as refrigerant, comprising:

-   -   a casing having a first and a second end section and an        intermediate section located therebetween;    -   an evaporator located at the first end section, adapted to        accommodate said water and allow evaporation of at least a part        of it to produce vapor, thereby removing heat from the remainder        of said water;    -   at least one compressor located at the second end section for        receiving said vapor through an intake conduit extending from        said evaporator to said compressor, and compressing said vapor,        the compressor being adapted to induce said evaporation by        maintaining vacuum at least at said intake conduit;    -   a condenser adapted for receiving the vapor from said        compressor, lowering its temperature thus condensing it back        into a liquid state; and    -   means allowing to create and maintain vacuum in said casing;

wherein said condenser is located in said intermediate section and saidintake conduit passes therethough.

Due to the unique arrangement of the heat pump elements within thecasing of the vacuum heat pump according to the present aspect of theinvention, the intermediate section of the casing otherwise wasted, isutilized to accommodate the condenser, which allows for minimizing theoverall size of the heat pump while maximizing the heat and masstransfer surfaces, as well as offering supreme heat and mass transfercoefficients.

The evaporator is based on a direct contact evaporation mechanism whichmay be in the form of agitator scoops adapted to spray the watertherein, extended plate surfaces sprayed with the water, or the like,adapted for increasing the evaporation surface area. The evaporator mayalso be adapted to receive feed water and discharge product water in theform of chilled water or ice slurry through appropriate respectiveinflow and outflow openings. Due to the fact that the evaporator is of adirect contact type, i.e. the water serves both as refrigerant and theproduct, the heat transfer process is highly efficient. Furthermore,when the product is in the form of ice slurry, the absence ofintermediate heat transfer surfaces between the refrigerant and theproduct prevents the freezing of water on such surfaces, which wouldnormally lower the efficiency of the overall heat transfer.

The compressor may be a centrifugal or axial flow compressor. One ormore compressors may be mounted together on a single mutual shaftallowing a higher temperature lift. Thus, if for example two compressorsare used, a first compressor is adapted to displace said vapor into thesecond compressor which is in turn adapted for further compressing ofthe vapor and its discharge into the condenser. In this case, the secondend section may be fitted with an inflow pipe adapted to deliverde-superheated water to the second compressor for more efficientcompression. Since the compressor discharges the vapor straight into thecondenser, the head losses usually created by a connecting pipe areeliminated.

Said condenser may comprise a packing having a large surface area andmeans for applying a coolant thereon. Such a packing may be locatedaround said intake conduit. The condenser may also be adapted to receivesuch a coolant from a pipe connected thereto. It may also be adapted toallow both the condensed vapor and the coolant to flow into a sumpstorage space, positioned at the end of said intermediate sectionadjacent to said first end section of the casing. The sump storage spacemay be fitted with an outflow opening adapted to receive a pipe forpumping out the water accumulated therein.

The intake conduit may be of any appropriate design. For example, it maybe advantageous for the intake conduit to have a wide end merging withthe circumference of the evaporator, a narrow end adjacent to saidcompressor, and a straight narrow portion therebetween. Such a designmay allow flow stabilization of the vapor entering the compressor. Theintake conduit's wide end may be fitted with one or more demisters whichare adapted for preventing droplet carryover into the compressor byfiltering out water droplets that are over a certain size. This size isnormally determined by the anticipated damage that might be inflictedupon the compressor should the droplets impact its blades. The demistermay be of the louver type, woven mesh type or the like and may beconnected to a heating mechanism for higher efficiency. External surfaceof the intake conduit facing the condenser may be shaped to form withthe casing said sump storage space.

According to one embodiment of the invention, the heat pump may bedesigned for use in a vertical orientation such that the second endsection is located above the intermediate and first end sections, thelatter serving as a pool for the refrigerant. In this case, dropletcarryover to the compressor may be largely prevented since most of thedroplets are pulled back into the evaporator simply by gravity, allowingoptional elimination of the demister. Furthermore, such an orientationallows the provision of a uniform vapor flow into the compressor throughthe intake conduit, raising the efficiency of the compressor. Thisadvantage may be further emphasized if the heat pump is designed to havean axial symmetry around a vertical axis extending between the first andsecond ends.

The heat pump may be operated in a closed or open cycle. Possibleapplications of the heat pump include, but are not limited to, its useas a compact water chiller, a compact ice-slurry maker, or a part of awater desalination installation, a part of a snow making or iceproduction facility, a combination of two or more of these applicationsor the like. For some of these implementations, any of the sections ofthe heat pump may be modified, as deemed necessary.

If the heat pump is used for producing slurry for snow making, it mayconstitute a part of a snow dome for indoor skiing and leisureactivities, said dome comprising a slope adapted for dispersion of saidslurry thereon and a water withdrawal facility adapted to withdraw waterfrom said slurry, to allow leaving wet snow on top of said slope forskiing thereon, dome comprising a plurality of dispersion valves adaptedfor dispersion of said slurry onto said slope and a slurry feed lineadapted to introduce the slurry into said valves; said facilitycomprising a set of drainage channels adapted for draining water out ofsaid slurry or wet snow, and a plurality of barriers disposed along theslope and adapted for impeding the water from said slurry and divertingit into said channels, thereby preventing flooding of the slope by theslurry water during dispersion of the slurry, and maintaining a lowwater level beneath the snowed slope by constant drainage of snow-meltwater. Said snow dome may also comprise one or more screens adapted tobe positioned on said slope in a removable manner for piling up of saidsnow.

A snow dome as described above constitutes another aspect of the presentinvention.

The water withdrawal facility in the snow dome may also be useful towithdraw snow-melt water from the slope. It may also comprise a storagetank in fluid communication with the drainage channels adapted tocollect water withdrawn from the slope. This tank may also be connectedto inlet/s of one or more slurry producing heat pumps, to produce slurryfrom the withdrawn water.

The angle of the slope may vary from dome to dome and may even beadjustable to suite the user's needs. The barriers may be of variousforms, e.g. angular, semi-circular, straight etc.

With the design of the snow dome as described above, snow thereon isallowed to melt and, subsequently, snow-melt water may be fed back intothe slurry production facility, making the refrigeration of the dome notobligatory as opposed to known facilities, whereby full indoor skiingand snow related activity in above zero degrees centigrade is madepossible. The environment of the snow dome is naturally refrigerated bythe meltdown of the snow dispersed on the slope. It should also be notedthat the dome may be further refrigerated should this be desired, andeven divert a portion of said snow-melt water for that particularpurpose.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how it may be carriedout in practice, embodiments will now be described, by way ofnon-limiting examples only, with reference to the accompanying drawings,in which:

FIG. 1 is a schematic cross-sectional view of a heat pump designed forthe production of ice slurry, in accordance with one embodiment of thefirst aspect of the invention;

FIG. 2 is a schematic cross-sectional view of the heat pump shown inFIG. 1 used with an ice slurry tank;

FIG. 3 is a schematic cross-sectional view of the heat pump of FIG. 1used for water desalination;

FIG. 4 is a schematic cross-sectional view of the heat pump of FIG. 1modified for supply of chilled water, in accordance with anotherembodiment of the first aspect of the invention;

FIG. 5 is a schematic view of a snow dome for indoor skiing inaccordance with another aspect of the invention; and

FIG. 6 is a schematic side view of the snow dome shown in FIG. 5 witherected screens.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Attention is first drawn to FIG. 1, where there is shown a schematiccross-sectional view of a vertically positioned heat pump (10), adaptedfor production of ice slurry. The heat pump comprises a casing (12) witha lower end section (2), an upper end section (4) and an intermediatesection (3).

The evaporator (20) is located at the bottom end section (2) and is inthe form of a cavity adapted to accommodate a certain amount of water(22), having a water inlet (21) and an ice slurry outlet (23). Theevaporator further comprises a set of scoops for agitation (26) adaptedto be powered by a motor (24) located outside the casing (12), and anoptional demister (28) located above the water (22) level adapted forfiltering water droplets over a certain size from the water vaporpassing therethrough.

The upper end section (4) houses a compressor (40) having a rotor (42),and compressor blades (43) mounted on a main shaft (49) adapted to bepowered by a motor (48) located outside the casing (12). The compressoris in fluid communication with the evaporator via an intake conduit (32)and is designed for maintaining vacuum within the evaporator (20) andthe intake conduit (32). The intake conduit (32) comprises a wideconical portion (32 a) with a first end merged with the circumference ofthe evaporator (20), and a narrow straight portion (32 b) with a secondend adjacent and leading to the compressor (40). The compressor furthercomprises at least one diffuser channel (44).

The intermediate section (3) of the heat pump (10) includes a condenser(30) and compressor intake conduit (32) passing therethrough, allowingfluid communication between the evaporator (20) and compressor (40). Onthe outside perimeter of the intake conduit (32) is a condenser (30),comprising a large surface area packing (34) adapted to increase heattransfer between a vapor and a coolant, a coolant distribution mechanism(36) adapted to spray said coolant on top of said packing (34), and acoolant inflow opening (31) adapted to be connected to a feed line (31a), supplying the condenser with the coolant. The condenser furthercomprises one or more vacuum means (39) adapted to be connected throughoutflow line (39 a) to vacuum pumps (not shown) designed for creating aninitial vacuum within the casing (12) prior to operation of the heatpump (10), and for the removal of non-condensable gasses from thecondenser (30).

In addition, the condenser (30) comprises a sump storage space (37)formed by the conical shape portion (32 a) of the intake conduit (32)and the casing (12) wall. The sump space comprises an outflow opening(33), adapted to be connected to an outflow line (33 a) which is, inturn, connected to a pump (35), both line and pump adapted for removingthe accumulated water sump (38) from the sump storage space (37). Thesump may be used for a number of implementations like a source fordistilled water or the like. Alternatively, the sump (38) may be removedall together to an external reservoir.

Prior to operation of the heat pump (10), the air within the casing (12)is removed through the vacuum means (39) and outflow line (39 a), andthe pressure within the casing (12) is lowered to near vacuum.Subsequently, the compressor (40) commences its operation, maintaining astate of vacuum within the space of the evaporator (20) and intakeconduit (32), inducing evaporation of water from the evaporator (20).

The agitator scoops (26) of the evaporator (20) spray the water (22) onto the evaporator walls (29) creating a larger surface area forevaporation. The vapor (not shown) created by evaporation of water fromthe evaporator walls (29) and pool surface is being displaced in anupward direction into the conical portion (32 a) of the intake conduit(32) due to the suction of the compressor (40). Most of the waterdroplets entrained in the vapor updraft are pulled back down into thewater (22) in the evaporator pool simply by gravity whereas theremainder of the droplets are trapped by the demister (28). Afterpassing the demister (28), the vapor passes through both wide conical(32 a) and straight narrow (32 b) portions of the intake conduit (32)and reaches the compressor (40).

When the vapor reaches the compressor (40), the vapor is compressed anddisplaced through the diffuser channels (44) into the condenser (30) ina downward direction towards the condenser packing (34). At the sametime, a coolant (not shown) is provided through feed line (31 a) anddistributed through the distribution mechanism (36) onto the packing(34) as well. As a result, a heat transfer process takes place betweenthe coolant and the vapor in which the vapor cools down and condenseswhile transferring heat to the coolant. After this heat transfer, thecondensed water and coolant drip down forming a sump (38) accumulated inthe sump storage space (37). The heat pump (35) draws the sump (38)through outflow line (33 a) outside the casing (12) where some of thesump (38) may be reused, after it is cooled by cooling means (not shown)and redirected back to feed line (21 a), some of the sump may bereturned through an optional overflow mechanism (not shown).

As a result of the process, heat is taken away from the water (22),transforming part of the water (22) into an ice slurry. The slurry ispumped away from the evaporator (20) through an outflow line (23 a)using a slurry pump (25). Since the process is continuous, water andcoolant are constantly being pumped into evaporator and condenser (20;30) through feed lines (21 a; 31 a) respectively, and sump (38) isconstantly being pumped out of the sump space (37) through outflow line(33 a).

Non-condensable gasses as well as the remainder of compressed vapor thathas not condensed are pumped out through vacuum means (39) in thecondenser (30). The NCG (Non-Condensable Gasses) and vapor are directedoutside the heat pump (10) and may be also used for a variety ofimplementations.

FIG. 2 Illustrates the use of the heat pump (10) with an ice slurry tank(50) adapted to be used as a low temperature reservoir. The outflow line(23 a) withdraws ice slurry from the evaporator (20) and feeds it intothe ice slurry tank (50) on its top side. When the slurry has beenintroduced into the tank (50), the cold water (54) from the slurry sinkdown to the bottom of the tank (50) causing the reduced ice slurry (52)to float on top of it.

The low temperature reservoir may be used in a number of applications,for example, in conjunction with an air conditioning unit or system (notshown) whereby the inflow (51) and outflow (53) lines, and the pump (55)are used for circulation of cold water between the tank (50) and the airconditioning system. Due to the use of ice slurry (54), the tank (50)required to store the low temperature medium, i.e. ice slurry, requiresmuch less space than in common systems using only cold water.

Another implementation of the heat pump (10) is shown in FIG. 3, wherethe heat pump is used for the purpose of water distillation inconjunction with an ice separator (80), comprising an internal portion(82) and an external portion (84) each adapted to hold ice slurry ofdifferent qualities. The separator (80) is further connected to a feedline (89) connected to the bottom portion of the separator (80) and totwo outflow pipes (81; 87) connected to the bottom of the externalportion (84) and top of the internal portion (82) respectively. In thisembodiment, a further use is also made of the sump (38) collected in thecondenser (30) of the heat pump for distillation purposes.

Since the heat pump (10) in the latter embodiment works essentially thesame as in the previous embodiments, only its operation and connectionto the external elements (70; 80) will be described:

In operation, the ice slurry withdrawn from the evaporator (20) throughoutflow line (23 a) is being pumped through feed line (89) using pump(25) into the internal portion (82) of the ice separator (80) where aseparation of the water from the ice slurry takes place, leaving a waterreduced ice slurry at the top of the internal portion (82) of theseparator (80). The water sinking down to the bottom of the externalportion (82) is withdrawn using outflow line (87) into feed line (21 a)of the heat pump (10). The water reduced ice slurry received at the topof the internal portion (82) is being carried away using outflow line(81) to be used for various implementations.

The sump (38) accumulated in the sump storage space (37) is withdrawnusing outflow pipe (33 a) and is pumped into feed line (31 a) using apump (35). However, a certain amount of sump is being redirected to anoutflow line (33 b) as distilled water intended for various purposes.The remainder of the sump is carried through the line (31 a) where itundergoes heat transfer in a heat exchanger (70) using a line (72). Theheat exchanger (70) is also used as a buffer for water purificationresulting in cool clean water which is moved through line (31 a) toenter the condenser (30) as the condenser coolant.

Another embodiment of the heat pump (10) is shown in FIG. 4, where theheat pump (10) is used as a chiller and has a modified evaporator and anenlarged upper end section (4). In this embodiment, the evaporatorcomprises a set of plates (67) having a large surface area and a set ofsprinlders (66) connected to a feed line (21 a). In operation, the waterfrom the feed line (21 a) is sprayed over the plates (67), allowingevaporation of the water. From the evaporator (20), vapor moves in anupward direction through the intake conduit (32) until it reaches thecompressor (30).

The upper end section (4) is shown containing a de-superheating chamber(45) housing a second compressor (80), which may be similar to theoriginal compressor (40). Both compressors (40; 80) are mounted on asingle shaft (49). An additional feed line (41 a) is connected to thede-superheating chamber (45) adapted to supply de-superheated water intosaid chamber using a distribution mechanism (47).

In such an embodiment the compressors (40; 80) are connected such thatin operation, the first compressor (40) directs the vapor upwardstowards the second compressor (80) as opposed to the previous embodimentwhere the vapor was directed to the condenser (30). The secondcompressor (80) further compresses the vapor and directs it into thecondenser (30) where the process continues much like in the firstembodiment. The addition of the compressor (80) to the heat pump (10)allows for a higher temperature lifts of the water (22) within the heatpump (10).

In FIG. 5 a snow dome (120) is shown of the kind where a heat pumpaccording to the first aspect of the invention or another heat pump maybe used, comprising a slope (121) having a plurality of barriers (122)disposed along it, a roof (123) supporting a slurry feed line (124), aplurality of dispersion valves (125) disposed along the feed line (124),drainage channels (126) disposed on both sides of the slope (121), awater tank (127) and two ice slurry production heat pumps (129). Theheat pumps are connected to the tank (127) by a feed pipe (128) and tothe feed line (124) by an outflow pipe (130).

In operation, as shown in FIG. 6, screens (131) are erectedintermittently along the slope (121) prior to dispersion of ice-slurrythereon. The heat pump (129) receives feed water from the water tank(127) through line (128) and produces ice slurry containing a high levelof ice crystals. The slurry is then pumped through a pipe (130) into theslurry feed line (124), and using the dispersion valves (125), isdistributed onto the slope (121).

The melt water from the ice-slurry form a water layer (132) on which theslurry is free to slip in a downward direction, indicated by arrow(134). The screens (131) prevent the slurry from slipping, allowing onlywater (132) to drip down, resulting in the piling of wet snow (133)against the screens (131). The water (132) dripping passed the screens(131) are blocked by the barriers (122) and directed into the drainagechannels (126) from which it is fed into the water tank (127).

Once the piles (133) have been formed, the screens (131) may be removedand the piles may be groomed manually or by mechanical means (not shown)to create an even layer of snow (133) on the slope (121) allowing skiingand snow related activities. During the operation of the dome (120), thesnow (133) on the slope (121) is constantly melting. The snow-melt water(132) seeping down the slope (121) are blocked by the barriers (122) anddirected into the drainage channels (126), thus a low water level on theslope (21) is maintained. The water from the drainage channels (126) isfed back into the water tank (127) where the entire process may repeatitself.

Since the snow (133) on top of the slope (121) is allowed to melt,skiing and snow related activities may be carried out within the dome(120) in above zero degrees centigrade, and refrigeration of the dome(120) environment is not obligatory. Furthermore, the dome (120) isnaturally cooled by the latent heat taken by the snow (133) in theprocess of melting. Should further refrigeration of the dome (120) bedesired, part of the water from the tank (127) may be diverted for suchpurposes. In addition, the snow dome (120) may be fitted with anair-conditioning system adapted for de-humidifying the air within thedome.

It should be noted that the screens (131) and barriers (122) may be ofvarious shapes and form allowing the functionality as described in theabove specifications, e.g. angular, semi-circular etc.

Those skilled in the art to which this invention pertains will readilyappreciate that numerous changes, variations and modifications can bemade without departing from the scope of the invention mutatis mutandis.

1-11. (canceled)
 12. A snow deposition system comprising: at least oneslurry production facility arranged to produce snow slurry from water; adelivery system arranged to drop snow slurry obtained from the at leastone slurry production facility onto a slope having screens arranged toreceive and accumulate the dropped snow slurry; and a drainage systemarranged to collect and drain from the slope water from the dropped snowslurry, to leave behind drained snow, and further arranged to direct thedrained water to the slurry production facility to yield additional snowslurry.
 13. The snow deposition system of claim 12, wherein the drainagesystem comprises a plurality of barriers associated with a plurality ofchannels, the barriers arranged to divert water from the slope to thechannels.
 14. The snow deposition system of claim 13, wherein thedrainage system comprises at least one storage tank in fluidcommunication with the channels and with the at least one slurryproduction facility, the at least one storage tank arranged to receivedrained water from the channels and deliver the received water to the atleast one slurry production facility.
 15. The snow deposition system ofclaim 12, further comprising at least one disperser arranged to dispersethe left behind snow on the slope.
 16. The snow deposition system ofclaim 12, wherein the delivery system comprises a plurality ofdispersion valves arranged to disperse the slurry onto the slope
 17. Asnow dome comprising the snow deposition system of claim 12, arranged tooperate the snow deposition system within a closed space.
 18. The snowdome of claim 17, arranged to maintain a temperature of the closed spaceabove 0° C.
 19. The snow dome of claim 17, wherein the slope has aplurality of adjustable slope angles.
 20. The snow dome of claim 17,further comprising an air conditioning system arranged to de-humidifythe closed space.
 21. The snow deposition system of claim 12, whereinthe at least one slurry production facility comprises a compact heatpump using water as refrigerant, comprising: a casing having a first endsection and a second end section and an intermediate section locatedtherebetween; an evaporator located at the first end section, configuredfor containing said water and allowing evaporation of at least a part ofthe water therefrom to produce vapor, thereby removing heat from theremainder of the water; at least one agitator scoop located within saidevaporator, said scoop being used for both agitating and for sprayingthe water within the evaporator for increasing evaporation surface area;one or more demisters installed between the evaporator and thecompressor, provided with a heating mechanism; one or more compressorslocated at the second end section and provided with an intake conduitextending from the evaporator to the compressor, configured to inducethe evaporation by maintaining vacuum at least at the intake conduit,the compressor being further configured for receiving the vapor throughthe intake conduit after passing through the heated demister andcompressing it; a condenser located in said intermediate section suchthat said intake conduit passes therethrough, said condenser beingconfigured for receiving the compressed vapor from the compressor,lowering its temperature and condensing it back into a liquid state, anda vacuum machine arranged to create and maintain vacuum in the casing.22. A method of delivering snow to a slope, comprising: dropping snowslurry obtained from a slurry production facility onto the slope;preventing the dropped snow slurry from sliding down the slope byplacing screens arranged to receive and accumulate the dropped snowslurry; draining water from snow slurry accumulating on the slope toleave behind drained snow on the slope; delivering the drained waterback to the slurry production facility to yield additional snow slurry;and dispersing the left behind snow accumulated by the screens on theslope.
 23. The method of claim 22, wherein the draining water comprisesdiverting water from the slope and channeling the diverted water for thedelivery back to the slurry production facility
 24. The method of claim22, wherein the dropping snow slurry is carried out periodically. 25.The method of claim 22, carried out in a closed space.
 26. The method ofclaim 25, further comprising de-humidifying the closed space.
 27. Themethod of claim 25, further comprising maintaining a temperature of theclosed space above 0° C.